The present invention relates to an electronic control apparatus which is adapted to be mounted on a vehicle for controlling an anti-lock brake apparatus, a traction control apparatus and the like.
FIG. 3 shows, in a block form, an example of a conventional electronic controller in the form of a vehicle slip control apparatus as described in Japanese Patent Laid-Open No. 1-148645. In this figure, information processed by an anti-look control means 1 and a traction control means 2 are communicated to each other as serial data. Specifically, wheel-speed sensors 1 provided for corresponding road wheels of a vehicle each generate an output signal representative of the rotational speed of a corresponding road wheel which is input to an interface 5 of a first control box 8 and converted there into a binary code to provide a pulse signal. The pulse signal thus produced is fed to the anti-lock control means 1 which successively calculates, based on the information thus input, the rotational speed, the acceleration and deceleration of each road wheel, the estimated speed of the vehicle and the like. Based on the results of these calculations, the antilock control means 1 then controls a first actuator 6 so as to properly adjust brake forces applied for braking the respective wheels. Also, the results of the calculations of the anti-lock control means 1 are successively sent to a first serial data transmission means 10 in a parallel fashion. The first serial data transmission means 10 transmits the thus supplied parallel data to a second serial data transmission means 11 inside a second control box 9 in a time-shared multiplex transmission manner. The serial data transmission means 11 converts the serial data thus received into parallel data which is in turn fed to the traction control means 2 so as to control a second actuator 7 for adjusting the traction force of the engine and/or brake forces.
With the above-described conventional vehicle slip control apparatus as constructed above, information communicated between the anti-lock control mean 1 and the traction control means is of very much importance from the control point of view. Therefore, in preparation for the case in which data transmission between the anti-lock control means 1 and the traction control means 2 becomes faulty, each of the control means 1, 2 is provided with some failsafe means such as a control-disabling means for ensuring the operational stability of the vehicle. However, such failsafe means are generally controlled by a microcomputer using a certain software, so it is not necessarily assured that if there arises an abnormality or malfunction in one of the software-controlled failsafe means, the transmission and control output of the faulty or abnormal failsafe means is made to shift to the safe side of operation. In addition, since the actuators 6, 7 particularly control the brakes, it is most important to ensure safe operation thereof.